2 Month Preseason, Yet Positional Matchmaking Is Released After It Ends?

What was the point of a two month preseason if the only significant change made during it was tower plating? Like positional matchmaking is probably one of the most influential changes I've seen since I started this game, and they just decide to drop it with virtually no testing AFTER preseason? Why did we not use the excruciatingly long preseason to test an update this big and find the many flaws in it (inting autofilled games > dodging and duoing as each other's main roles for lower ranks and basically free LP).